Liquid-crystal (L-C) polymers are known to form mesophases having one- and two-dimensional order as disclosed by Flory, P. J., Advances in Polymer Science, Liquid Crystal Polymers I; Springer-Verlag: New York (1984) Volume 59; Schwarz, J. Mackromol, Chem. Rapid Commun. (1986) 7, 21. Further, mesophases are well known to impart strength, toughness and thermal stability to plastics and fibers as described by Kwolek et al in Macromolecules (1977) 10, 1390; and by Dobb et al, Advances in Polymer Science, Liquid Crystal Polymers II/III (1986) 255(4), 179.
While L-C polymers have been widely studied, their potential utility as coatings binders seems to have been overlooked. Japanese patents claiming that p-hydroxybenzoic acid (PHBA), a monomer commonly used in L-C polymers, enhances the properties of polyester powder coatings are among the very few reports that may describe L-C polymers in coatings; Japanese Kokai 75/40,629 (1975) to Maruyama et al; Japanese Kokai 76/56,839 (1976) to Nakamura et al; Japanese Kokai 76/44,130 (1976) to Nogami et al; and Japanese Kokai 77/73,929 (1977) to Nogami et al.
Further, coatings binders with lower viscosities which provide harder coatings and less drying times through combinations of amorphous polymers with mesogenic groups are not disclosed in the prior art and are to be desired.
An object of this invention is to provide improved coatings binders comprising amorphous polymers in combination with mesogenic groups.
A further object of this invention is the provision of improved coatings binders comprising low Tg amorphous polymers in combination with mesogenic groups.
A more particular object of this invention is to provide cross-linked and uncross-linked enamels of improved hardness and impact resistance.
Other important objects are to provide high solids/low viscosity coatings formulations with fast drying coatings which provide harder resultant coatings.
Still further objects and advantages of the invention will be found by reference to the following description.